Carbonxt nears permit for coal-based carbon plant in W.Va.

The West Virginia Department of Environmental Protection is taking public comment until May 10 on a draft air permit covering a cutting-edge, 26,200-ton per year activated carbon production facility to be located at the Bayer CropScience plant in Kanawha County.

The permit is being sought by Carbonxt Inc. “The proposed plant will produce activated carbon which has been chemically enhanced to improve its performance as a means for reducing the emission of [hazardous air pollutants] HAPs from electric power generating plants and other coal burning facilities,” said a DEP engineering report on the project.

The raw material for the process is stoker sized coal which has been double screened at the mine to produce particles in the range of 1 1/4 inch x 1/4 inch. Delivery trucks will discharge coal loads onto a grizzly screen which will allow the coal to drop by gravity onto a moving shuttle conveyor that will convey the coal to a bucket elevator and then to one of three storage silos.

Control of the emissions will be maintained by producing a slight negative pressure within the delivery room by means of a blower that will pull air from the room through a pulse jet baghouse. Coal from the storage silos is recycled back to a surge hopper and then to a crusher.

The coal crusher will be a hammer mill type system capable of crushing 20 tons per hour of stoker size coal. The crushed coal is returned to the storage silos. Both the crusher and storage silos are controlled by baghouses. Crushed coal from the storage silo will be fed forward to a surge bin and then to one of two rotary calciners where the coal is indirectly heated to a high temperature in the presence of injected steam to drive off all of the volatile matter contained in the raw coal.

The volatile matter and gasification reactions which occur within the rotary calciners amount to approximately 66% of the weight of the raw coal. The remaining solids (in the form of activated carbon) will amount to about 34% of the weight of the raw coal. Each of the two rotary calciners has its own independent control system for processing the gaseous matter produced by the calciners. The gaseous matter from the rotary calciner is sent to a thermal oxidizer where it is mixed with injected natural gas and air and burned.

The solids (ash) from the thermal oxidizer are sent to a direct water quench cooler, then a venturi scrubber, then to two dual packed bed caustic scrubbers and are then discharged to the atmosphere. The liquids from the venturi scrubber and the dual packed bed scrubbers are collected and sent to filter beds where the solids are removed and sent to a landfill. The liquids from the filter bed will be either recycled to the quench cooler or sent to the Bayer CropScience wastewater treatment facility.

The activated carbon from the rotary calciner is to be sent to an indirect cooler and then an activated carbon hopper where the solids are combined with those from the other rotary calciner. Next, the activated carbon is dropped onto a belt conveyor where it is mixed with an additive to enhance its performance characteristics. Then the material is sent to a micronization mill where it will be reduced in size to a particle distribution of 95% minimum through 325 mesh. The material is captured by a baghouse from which the final product is pneumatically conveyed to the activated carbon storage bins. The final product is removed from the plant by truck.

Said the website of the Australia-based Carbonxt Inc. parent company: “Carbonxt Group Limited (CXT) is participating in the global effort to reduce environmental pollutants through the development of proprietary clean coal technologies used in the production of activated carbon. Carbonxt’s activated carbons are primarily produced for use in applications such as water treatment and capturing mercury emissions from coal-fired power stations. In fact, activated carbon injection (ACI) is the most widely accepted method used to reduce mercury emissions from coal-fired power stations, a significant anthropogenic source of the toxin.”

Carbonxt Group is an unlisted public company based in Sydney, Australia, that was established to commercialize its proprietary clean coal technology. “Through its US-based subsidiary, Carbonxt Inc., CXT Carbonxt has constructed a technical facility in West Virginia, USA,” the company website said. “This facility operates in preparation for the imminent construction of its first commercial plant. The commercial plant will also be located in West Virginia, with an annual capacity to produce 20 kilotons of Activated Carbon and an expansion capacity for an additional 20 kilotons.” The website said the company should be able to “initiate” this first commercial plant in the first half of this year.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.